Buying guide
5-inch vs 6-inch gutters: which size does your Missouri home need?
If your gutters overflow during hard rain even when they are perfectly clean, they are almost certainly undersized. Gutter capacity is a drainage calculation, not a style choice, and it comes down to how much water your roof delivers and how fast.
What actually determines the size
Three factors decide it: the roof area draining into that run, the roof pitch, and local rainfall intensity. A steep roof throws water faster and farther than a shallow one, so it needs more capacity for the same square footage. Metal roofs behave the same way — water sheets off them with very little friction.
- 5" K-style: right for most standard single-family homes with moderate roof pitch
- 6" K-style with 3x4 downspouts: large roof areas, steep pitches, metal roofs, or runs that have historically overflowed
- Downspout count matters as much as gutter width — a 6" gutter feeding one undersized downspout still backs up
How much more does 6-inch cost?
The material itself is a modest step up, but the practical cost difference comes from the whole package: wider gutter, oversized downspouts, and more hangers to carry the extra water weight. Expect an oversized system to sit toward the higher end of the installed per-foot range rather than doubling your price.
It is worth it when it stops overflow. Replacing gutters twice because the first set was undersized is the expensive option.
Signs your current gutters are too small
You do not need a calculator if the house is already telling you. Watch during the next real downpour.
- Water sheets over the front lip during heavy rain even when clean
- Water shoots past the gutter entirely at valleys where two roof planes meet
- Hangers pull loose repeatedly on the same run
- Downspouts gurgle and back up rather than running steadily
Valleys deserve special attention
Where two roof planes meet, a valley concentrates runoff from both into a narrow stream. That single point can overwhelm an otherwise adequate gutter. Often the right answer is not resizing the whole house but adding a downspout near the valley, or upsizing only the run that receives it.
This is the kind of thing that gets sorted out during an on-site measurement, which is why we size gutters at the house rather than over the phone.